import 'package:flutter/material.dart';

void main(List<String> args) {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  bool flag = true;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Animated Opacity Demo"),
      ),
      body: Center(
        child: AnimatedOpacity(
          curve: Curves.easeInOut,
          opacity: flag ? 1 : 0,
          duration: const Duration(seconds: 1),
          child: Container(
            width: 300,
            height: 300,
            color: Colors.blue,
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(() {
            flag = !flag;
          });
        },
        child: const Icon(Icons.opacity),
      ),
    );
  }
}
